In various mobile and stationary applications, water systems including toilet systems are provided for use by persons occupying the mobile or stationary space served by the water systems. Particularly, in the context of a mobile passenger transport vehicle, such as a train, a bus, a ship, or especially a passenger aircraft, an onboard water system includes a toilet system for the disposal of urine and fecal waste from the passengers, as well as a drinking water system supplying fresh potable drinking water and a secondary water use system, for example providing wash water to handwash basins, galley sinks, or even dishwashers, showers, or the like.
In this regard, various terms need to be defined, for use throughout this application. Fresh water or potable water refers to water that is clean, fresh, and free of biological and other contaminants, and thus is suitable as drinking water for the passengers. This fresh potable water is stored in a fresh water tank in the aircraft for use during a flight. Through the use of the toilet system, so-called blackwater results, which is water contaminated with urine, feces, other waste materials, or various contaminants or residues, through which the water is considered biologically contaminated and hazardous. Through the use of handwash basins, galley sinks, and the like, so-called graywater arises, which is the potable drinking water or secondary use water which drains from the drinking water system or the secondary use system, e.g. from the handwash basins, galley sinks and the like, and which is slightly contaminated with soap, detergent, and relatively low amounts of various wastes and contaminants (for example arising from the washing of hands or the like). The term wastewater is a general term that covers both graywater and blackwater. Both the graywater and the blackwater, but especially the blackwater in a higher concentration, are contaminated with various germs, which generally refers to any biological contaminants herein, including bacteria, viruses, yeasts, protozoans, microbes, molds, fungi, or any other biological contaminants.
The wastewater that arises during use of the passenger transport vehicle, e.g. during a flight of a passenger aircraft, often needs to be at least temporarily stored in a wastewater storage tank in the vehicle, e.g. in the aircraft. Due to the biological contamination of the wastewater with various germs as mentioned above, the germs can multiply tremendously during the temporary storage of the wastewater, which leads to possible infection problems, odor problems, and the like. Similarly, surfaces of the various water systems and especially the toilet system, which come into contact with various contaminants such as the toilet surfaces coming into contact with urine, feces, blood, or the like, are thereby subject to biological contamination with various germs. This also causes an odor problem, and presents a hazard of infection to any person who comes into contact, i.e. skin contact, with the contaminated surface. These surfaces are especially the externally exposed surfaces of urinals, toilet bowls, and toilet seats.
Conventional urinals and toilets are subjected to cleaning and disinfection procedures at time-variable intervals, which are often inadequate to satisfy the hygienic demands. For example, during periods of high use of a public toilet, the toilet surfaces may become unacceptably contaminated with various germs arising from the soiling of these surfaces with urine, feces, blood, or other waste materials. This is unsanitary, unhealthful for the subsequent users of the toilet, and also esthetically unacceptable. A method and an apparatus for cleaning toilet surfaces, and especially the toilet seat, at regular intervals, especially corresponding to the frequency of use of the toilet, are needed.
The conventional cleaning and disinfection procedures involve the use of detergents and chemicals in liquid solutions for physically cleaning waste residues from the contaminated surfaces and killing germs remaining on the surfaces. Such detergents and chemicals further load the wastewater and make it more difficult to later biologically process and dispose of the wastewater. Namely, the detergents and chemicals themselves represent chemical and environmental hazards that must be dealt with downstream from their point of use. Also, any residues of such detergents and chemicals remaining on the affected toilet surfaces could be hazardous to any person making skin contact with these surfaces.
There is a strong demand among users of public toilets, including aircraft toilets, for avoiding personal contact of the toilet user with toilet surfaces, e.g. toilet seat surfaces, which are unhygienic or of questionable hygienic nature. Conventional solutions of this problem involve the use of paper seat covers as well as disinfection solutions that are to be applied onto the toilet seat by the user directly before using the toilet. Also, automatic or self-cleaning toilet seats have been offered, in which water is applied to the toilet seat in order to flush or rinse the toilet seat in a mechanical cleaning manner, but without any germ-killing effect. Furthermore, or alternatively, chemical disinfectants can be applied onto the toilet seat.
As a separate development, German Patent Laying Open Document DE 100 48 299 A1 discloses a method and an apparatus for electrolytic disinfection of potable drinking water, secondary use water, and wastewater, by subjecting the water to an anodic electrolytic process, whereby the cathodic formation of hydrogen is prevented by the use of gas diffusion electrodes as the cathode. The reference explains that the electrolytic process disinfects the water by killing microorganisms due to the effect of an electrical current introduced into the water through the electrodes. The particular disinfecting effects can involve the anodic generation of disinfecting agents out of the water itself or substances dissolved in the water, as well as direct killing of the microorganisms through contact with the electrodes or due to the shifted pH value of the water in proximity to the electrodes. This process is also known by the terms electrochemical disinfection, anodic oxidation, and weak current electrolysis. The main point of the reference is to avoid the generation of hydrogen at the cathode during the electrolytic treatment, which occurs in all of the recognized prior art electrolytic water disinfection methods.